1. Field of the Invention
The present invention relates generally to radio frequency (RF) transmitters.
2. Background Art
High-power transmitters require a power amplifier (PA) that can produce a high-voltage signal. Conventional high-power transmitter topologies use a voltage-input PA, such as a common-emitter/source PA or a variation thereof, that is cascaded after the transmitter. Commonly, voltage-input PAs provide non-linear amplification, especially in the B or AB classes of operation. As such, complex linearization techniques (e.g., pre-distortion) are needed in order to achieve specified transmitter EVM (Error Vector Magnitude) and ACPR (Adjacent Channel Power Ratio) mask.
There is a need therefore for improved transmitter topologies for high transmission power applications.
The present invention will be described with reference to the accompanying drawings. Generally, the drawing in which an element first appears is typically indicated by the leftmost digit(s) in the corresponding reference number.